Engine governors are well known which are adapted to limit the engine speed to a preset top speed with only brief excursions above the top speed. Such governors typically operate to regulate the flow of fuel to the engine and are of the type which comprise a throttle closing means which overrides the manually actuable throttle. A governor of this type is disclosed in my U.S. Pat. No. 4,523,564 granted June 18, 1985. The governor of this patent is especially adapted for use in automotive vehicles with either spark ignited engines or diesel engines.
In the use of such vehicle engine governors, it is not uncommon for the vehicle driver to attempt to disable the governor so that the vehicle can be operated at speeds above the top speed set by the governor. One way to disable the governor is to cut the supply voltage line to the governor. Aside from driver tampering, it is possible that the voltage supply to the governor would be cut off by reason of a malfunction. In the prior art, it is known to discourage drivers from tampering with the governor by causing the engine to shut down if the voltage supply to the governor is interrupted. It is known, for spark ignited engines, to connect the ignition coil in series through the battery supply line for the governor so that if the supply line is cut, the ignition voltage is interrupted and the vehicle cannot be driven. It is also known for diesel engine governors to use a shut-down solenoid connected to the battery voltage through the governor supply line so that if the supply line is cut the solenoid drops out and shuts off the fuel. In the Marie U.S. Pat. No. 3,547,216 granted Dec. 15, 1970, a system is disclosed with an ignition resistance wire inside the governor housing to prevent burn out of the ignition primary coil. If the driver attempts to use a jumper wire from the battery to the ignition coil after cutting the voltage supply line to the governor, the bypassing of the resistance wire will cause the coil to burn out.
In a fast idle device for engine warm up operation, as distinguished from top speed limiting governors, it is known to use a ratchet mechanism for holding the throttle at a fast idle position until certain engine conditions obtain and then releasing it to a slower idle position. Such an arrangement is disclosed in Masaki U.S. Pat. No. 4,368,704 granted Jan. 18, 1983.
Shutting down the engine in response to the loss of governor supply voltage or other malfunction is undesirable in that it leaves the vehicle inoperative and stranded. It is desirable to provide a governor with the capability of allowing operation of the engine at a reduced limiting speed even though the governor becomes inoperative.
A general object of this invention is to provide an improved top speed limiting governor which overcomes certain disadvantages of the prior art.